The present invention relates to an improved veneer paste used primarily in dentistry.
Self-cured polymeric veneer material has gained broad acceptance for use in preparing and repairing dental appliances, such as crowns and bridges, as is described by Milnes et al in U.S. Pat. No. 4,650,550. Such materials have good abrasion resistance, color stability, impact strength, bending strength and micro-hardness suitable for their use as a replacement for dentition similar to that described in U.S. Pat. No. 3,825,518 to Foster and in European Patents EP 26398, EP 11734 and EP 11735 to Bayer; and EP 33750 to IVOCLAR.
It has been found, however, that prior art heat cured pasty veneer materials are subject to interdental cracks, and surprisingly, it has been found that such interdental cracks can be substantially reduced or eliminated by the use of a veneer composition that is cured at relatively high temperatures, and contains a milled organic filler having particle sizes in a particular range. It is believed that the irregular (fractured, split or crushed) shape and size distribution of the milled organic fillers used in the composition provide the observed improved properties.
It is an object of the present invention to provide an improved heat cured pasty veneer material that is resistant to interdental cracks.